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What Is Biogas?

Biogas is actually a mixture of gases, usually carbon dioxide and methane. It is produced by a few kinds of microorganisms, usually when air or oxygen is absent. (The absence of oxygen is called “anaerobic conditions.”) Animals that eat a lot of plant material, particularly grazing animals such as cattle, produce large amounts of biogas. The biogas is produced not by the cow or elephant, but by billions of microorganisms living in its digestive system. Biogas also develops in bogs and at the bottom of lakes, where decaying organic matter builds up under wet and anaerobic conditions.

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In Todays world we can save on our electricity bills by switching to alternative sources of power.

Circuit of solar panel based charger





Slolar panel described here is capable of delivering a power of 5 watts. At full sunlight, the solar panel outputs 16.5V. It can deliver a current of 300-350 mA. Using it you can charge three
types of batteries: lead acid, Ni-Cd and Li-ion. The lead-acid batteries are commonly used in emergency lamps and UPS.

The working of the circuit is simple. The output of the solar panel is fed via diode 1N5402 (D1), which acts as a polarity guard and protects the solar panel. An ammeter is connected in series between diode D1 and fuse to measure the current flowing during charging of the batteries. As shown in Fig

we have used an analogue multimeter in 500mA range. Diode D2 is used for protection against
reverse polarity in case of wrong connection of the lead-acid battery. When you connect wrong polarity, the fuse will blow up.

For charging a lead-acid battery, shift switch S1 to ‘on’ position and use connector ‘A.’ After
you connect the battery, charging starts from the solar panel via diode D1, multimeter and fuse. Note that pulsating DC is the best for charging lead-acid batteries. If you use this circuit for charging a lead-acid battery, replace it with a normal pulsating DC charger once a week. Keep checking the water level of the lead-acid battery. Pure DC voltage normally leads to deposition
of sulphur on the plates of lead-acid batteries.

For charging Ni-Cd cells, shift switches S1 and S3 to ‘on’ position and use connector ‘B.’ Regulator IC 7806 (IC1) is wired as a constant-current source and its output is taken from the middle terminal (normally grounded). Using this circuit, a constant current goes to Ni-Cd cell for charging. A total of four 1.2V cells are used here. Resistor R2 limits the charging current.


For charging Li-ion battery (used in mobile phones), shift switches S1 and S2 to ‘on’ position and use connector ‘C.’ Regulator IC 7805 (IC2) provides 5V for charging the Li-ion battery. Using this circuit, you can charge a 3.6V Li-ion cell very easily. Resistor R3 limits the charging current.

This type of battery is different from a conventional car battery, as it is designed to be more tolerant of the kind of ongoing charging and discharging you would expect when you have variable sunshine from one day to the next.

The CIRCULATORY system connects all other systems. This
system performs four (4) principal functions:

• Transportation of oxygen and carbon dioxide
• Distribution of nutrients and transportation of wastes
• Maintenance of body temperature
• Circulation of hormones

Three general components:

• FLUID (blood) in which materials are transported
• System of BLOOD VESSELS in which the fluid moves in
• PUMP – (heart) that pushes fluid throughout system

The cardiovascular system = heart + blood vessels + blood

CIRCULATORY SYSTEM:

a) Pulmonary circuit: blood from RIGHT side (low OXYGEN) pumped
to LUNGS to pick up oxygen (release CO2)

b) Systemic circuit: blood from LEFT side (high OXYGEN) pumped
through body


-------------------------- Zoom image size by left click on image--------------------------
Heart Structure:

HEART: a double pump

a) RIGHT: pulmonary circuit

b) LEFT: systemic circuit



A large MUSCLE called the SEPTUM separates both sides.

The heart is divided into four (4) chambers:

• ATRIA: top two chambers, thin walls, RECEIVE blood
• VENTRICLES: bottom two chambers, thick walls, PUMP blood

VALVES: these are found between atria and ventricles and where ventricles empty into arteries that leave the heart ex. Atrioventricular valves: a) bicuspid valve- between RA and RV

tricuspid valve- between LA and LV
Semilunar valves: found between ventricles and arteries




Function of Valves:

• to ensure blood flows in ONE DIRECTION only
• prevents blood from going the wrong way

BLOOD VESSELS

There are THREE main types of blood vessels:




ARTERIES

• carry blood AWAY from the heart
• THICK walls (extra muscle)
• blood under high pressure
• largest called the AORTA
• most have HIGH amounts of OXYGEN except pulmonary artery (low O2 – goes to lungs)
• ARTERIOLES: small arteries

CAPILLARIES:

• smallest blood vessels
• where exchange of materials between blood and cells occurs
• one cell thick

VEINS:

• carry blood BACK to the heart
• THIN walls (less muscle)
• blood under LOW pressure
• contain VALVES to keep blood moving in one direction

BLOOD CELLS:


WBC: - white blood corpuscles

• -many types, called LEUKOCYTES
• -function: protect the body from invading microorganisms and toxins
• -cells have a nucleus

RBC: -red blood corpuscles

• -contain hemoglobin: an iron-containing protein which helps blood carry OXYGEN and CARBON DIOXIDE
• -with oxygen the blood is bright red
• -with carbon dioxide blood is dark red
• -cells do NOT have a nucleus

PLATELETS: - small cell fragments (not really true cells)
- job: help blood CLOT by working with SERUM proteins